I have been doing some research for a GL4 oil in my Muncie transmission and started looking at synthetic gear oils after not finding many GL4 dino oils. Out of all the GL4 synthetics out there in a 75/80w-90 weight oil, Royal Purple Max gear 80w-90 was the only one that I could find that had the viscosity closest to a dino gear oil which is what I am looking for to lessen the chance for leaks in my Muncie trans. Plus they say right on their site that it is compatible with the yellow metals in transmissions. The only thing I am not sure about and is why I am posting is the Limited Slip Additive that is in the Max Gear oil. RP Purple Max Gear comes already mixed with LS additive in it which is great for a posi differential, but I need to use it in my Muncie manual transmission. Can anyone tell me if this additive would effect the performance and drive ability in the trans? Would this additive make the syncros too slippery to engage the gears? Has anyone used Max Gear in their manual trans with or without any issues? RP says it is safe to use, but I wanted to hear what you guys thought and see if anyone has used it before in their manual trans. I am running out of other options for a GL4 gear oil for my trans. thanks for the help
RP Max Gear in a Manual Transmission
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Originally Posted By: SR77
RP Purple Max Gear comes already mixed with LS additive in it which is great for a posi differential, but I need to use it in my Muncie manual transmission. Can anyone tell me if this additive would effect the performance and drive ability in the trans? Would this additive make the syncros too slippery to engage the gears?
I tried it in my old transmission and it made every gear grind. I also suspected the ls additive.
RP Purple Max Gear comes already mixed with LS additive in it which is great for a posi differential, but I need to use it in my Muncie manual transmission. Can anyone tell me if this additive would effect the performance and drive ability in the trans? Would this additive make the syncros too slippery to engage the gears?
I tried it in my old transmission and it made every gear grind. I also suspected the ls additive.
MolaKule
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Can anyone tell me if this [LS] additive would effect the performance and drive ability in the trans? Would this additive make the syncros too slippery to engage the gears?
Yes it will affect it.
1. This is NOT the correct friction modifier for manual transmissions, it is designed to be used ONLY in differential transmissions.
2. I know of no one who recommends diffy fluid in a manual transmission; diffy lubes don't have the right viscosites nor the correct friction modifiers.
Quote:
Manual Transmission fluids use a different friction modifier for synchro engagement, a modifier that does NOT contain the same chemicals as differential lubes.
Differential lubes use friction modifiers to reduce mechanical and fluid friction and add some anti-shudder friction modifier for limited slip, both very different chemical compounds.
Manual Transmission fluids use a different friction modifier for synchro engagement, a modifier that does NOT contain the same chemical compounds as do differential lubes.
Both lubes contain the same EP additives, just in different strengths or additive ratios.
Most manual transmission "specific" fluids (GL4) contain about 40% to 60% of the EP additive of differential lubes (GL5) with inactive or buffered sulphurs. GL4 has come to infer a gear lube with the above percentages of EP additive. The exception of course is ATF fluid used in some of the newer transmissions.
You also have to consider the viscosity of the fluid that the transmission was designed for. The spectrum now ranges from ATF to 75W90 viscosities.
Ever since the synchromesh-type fluids appeared on the scene (such as the GM Synchromesh fluid), drivers have had better shifting due to better synchro engagement, attributed to the specialized friction modifier used in these lubes. This specialized friction modifier is better for metallic and composite synchros in terms of shifting and life.
A diffy 75W90 (GL5) usually has a higher viscosity than does an mtl in the same advertized weight.
So a differential lube may not kill your transmission, but it is not the optimum lube.
Yes it will affect it.
1. This is NOT the correct friction modifier for manual transmissions, it is designed to be used ONLY in differential transmissions.
2. I know of no one who recommends diffy fluid in a manual transmission; diffy lubes don't have the right viscosites nor the correct friction modifiers.
Quote:
Manual Transmission fluids use a different friction modifier for synchro engagement, a modifier that does NOT contain the same chemicals as differential lubes.
Differential lubes use friction modifiers to reduce mechanical and fluid friction and add some anti-shudder friction modifier for limited slip, both very different chemical compounds.
Manual Transmission fluids use a different friction modifier for synchro engagement, a modifier that does NOT contain the same chemical compounds as do differential lubes.
Both lubes contain the same EP additives, just in different strengths or additive ratios.
Most manual transmission "specific" fluids (GL4) contain about 40% to 60% of the EP additive of differential lubes (GL5) with inactive or buffered sulphurs. GL4 has come to infer a gear lube with the above percentages of EP additive. The exception of course is ATF fluid used in some of the newer transmissions.
You also have to consider the viscosity of the fluid that the transmission was designed for. The spectrum now ranges from ATF to 75W90 viscosities.
Ever since the synchromesh-type fluids appeared on the scene (such as the GM Synchromesh fluid), drivers have had better shifting due to better synchro engagement, attributed to the specialized friction modifier used in these lubes. This specialized friction modifier is better for metallic and composite synchros in terms of shifting and life.
A diffy 75W90 (GL5) usually has a higher viscosity than does an mtl in the same advertized weight.
So a differential lube may not kill your transmission, but it is not the optimum lube.
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SR77 do not use RP Max Gear you will not be happy with it at all! It shifts like [censored] after about 10,000 miles max especialy when it is cold outside. Git yourself some Redline MTL or some MT90. Redlines MT90 is GL4 synthetic and is going to be about the same in viscosity as 70W90 gearlube while the MTL will be thinner. It is not the viscosity though that will cause leaks if your seals are in good shape it will not matter what you use the only way it will leak is if the seal are old and damaged. I have used Redline MTL/MT90 mixed 50/50 in Corvettes that have been restored and have never had a problem on a rebuilt transmission.
Quote:
2. I know of no one who recommends diffy fluid in a manual transmission; diffy lubes don't have the right viscosities nor the correct friction modifiers.
Thanks for the reply Molakule. This is why I am confused and am hoping to get more opinions on others that have actually used it. RP and many other companies actually recommend right on their site the use of gear oils in older transmissions like my Muncie. Most builders will tell you the same thing too, they are designed for a 75/80w-90 weight oil in them. The new manual trans oils like Syncromesh have much lower viscosities and it is my understanding that they are only for newer manual transmissions. I am hoping to here from others and get some real world experience of these synthetic gear oils with the LS additive in them because I am not sure why RP would recommend their Max Gear oils in a trans if the additive has the opposite effect on them.
2. I know of no one who recommends diffy fluid in a manual transmission; diffy lubes don't have the right viscosities nor the correct friction modifiers.
Thanks for the reply Molakule. This is why I am confused and am hoping to get more opinions on others that have actually used it. RP and many other companies actually recommend right on their site the use of gear oils in older transmissions like my Muncie. Most builders will tell you the same thing too, they are designed for a 75/80w-90 weight oil in them. The new manual trans oils like Syncromesh have much lower viscosities and it is my understanding that they are only for newer manual transmissions. I am hoping to here from others and get some real world experience of these synthetic gear oils with the LS additive in them because I am not sure why RP would recommend their Max Gear oils in a trans if the additive has the opposite effect on them.
John, thanks. I did look at MT-90 also but its seems to be on the thinner side and have read others complain about the clunky shifts. It might state that it is a 75w-90, but if you look at the spec sheet it looks to be a much thinner viscosity at 40C and 100C then a dino 80w-90 that I was told is recommended for my Muncie. I didn't have the trans built it was already in when i got the car, so i don't know much about it and thats why i am hesitant on putting something to thin in that might cause shifting issues or even find its way to the clutch or my garage floor! After hearing your experience with it i might have to look into it again, the reason i was asking about RP is because it is the only synthetic GL4 that i found that had a viscosity close to and dino 8w-90.
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Just go with the Sta Lube GL4 85W90 if you want to run a dino. They even have a GL4 SAE140 dino.
aquariuscsm, I am leaning toward a dino gear oil because of the thicker viscosity for my older trans, but RP seems to be just as thick unlike other synthetics out there, its just this LS additive thing that I need more info on. Hearing your experience is not too comforting, but hope to hear more either way. I emailed RP about it also asking about their recommendation of Max Gear in a trans with this additive in it, but I haven't heard back from them yet, hmmmm.
I think you missed my earlier post about Amsoil. It is a GL-4 based synthetic than will work in older manual transmissions.
My Muncie was fully rebuilt using new Masiero gears, and it cost me a bunch of $$$ to do. I would risk running any gear lube in it that could cause a problem.
The Amsoil is called "Synthetic Transmission and Gear Oil, SAE 75w-90 API GL-4"
It says on the label "Ideal for muscle car transmissions such as Muncie, Borg Warner, Saginaw, Ford Top Loader, Dearborn, and New Process"
I guess if you keep asking the same questions about RP, you will eventually get the answer you want.
My Muncie was fully rebuilt using new Masiero gears, and it cost me a bunch of $$$ to do. I would risk running any gear lube in it that could cause a problem.
The Amsoil is called "Synthetic Transmission and Gear Oil, SAE 75w-90 API GL-4"
It says on the label "Ideal for muscle car transmissions such as Muncie, Borg Warner, Saginaw, Ford Top Loader, Dearborn, and New Process"
I guess if you keep asking the same questions about RP, you will eventually get the answer you want.
While Amsoil is not my first choice I would use it any day over Royal Purple. I have used Redline,Royal Purple,M1,Havoline,Rotella,Penzoil and now SUperTech 75W90 and can honestly say hands down that every manual transmission I have tried Redline in it has outperformed the others in terms of shift feel. I have yet to find anything that shifts better. Now from a standpoint of wear protection I do not think it makes much of a difference. The cold shift charteristics of RP Max Gear are dreadfull after only 10,000 miles. As to old manual transmissions again the viscosity does not matter only the condition of the seals. If the seals are in good shape it will not matter what you puit in their. All the transmissions I have ever seen leak with synthetics had their origanal seals from the the 1950's,60's and 70's and the material was simply cheap and the seals where worn out,dry rotted etc....
In fact I would use almost any fluid even Walmart Supertech over RP Max Gear in a transmission since you will be paying a premium for sub par performance. In fact why even use a synthetic gear lube if you are worried about leaks? I believe Swepco makes a GL4 dino gear lube.
In fact I would use almost any fluid even Walmart Supertech over RP Max Gear in a transmission since you will be paying a premium for sub par performance. In fact why even use a synthetic gear lube if you are worried about leaks? I believe Swepco makes a GL4 dino gear lube.
motul 300 is also great
thanks for the Motul info. Have to look into it more, it does say that there is no LS additive in it.
I would not use this oil in a manual. Someone here tried it in a Nissan Altima and it seemed to be a poor performer:
https://bobistheoilguy.com/forums/threads/06-altima-se-r-6-speed.80479/
I wouldn't worry about viscosity at 40 degrees, just 100. And at that measurement I have the following data:
Royal Purple Max Gear: 14.5 or 16.5
Red Line Oil MT-90: 15.6
Don't see how the Red Line is really any thinner (especially depending on which RP number you believe).
https://bobistheoilguy.com/forums/threads/06-altima-se-r-6-speed.80479/
I wouldn't worry about viscosity at 40 degrees, just 100. And at that measurement I have the following data:
Royal Purple Max Gear: 14.5 or 16.5
Red Line Oil MT-90: 15.6
Don't see how the Red Line is really any thinner (especially depending on which RP number you believe).
Bror Jace, thanks. Maybe I am looking at this wrong, but my reasoning for looking at the Viscosity @ 40c was because this car is not a daily driver. It sits in the garage alot and only comes out on nice weekend days in the summer. Sits all winter too. So I was looking at the lower temps viscosity to try to find the thicker brand to hopefully prevent leaks while sitting, which I have been told is when old cars leak the most. I was told from the previous owner the builder said to use dino oil in it, but didn't see a problem using a synthetic if I could find one that has the same viscosity specs. Does this make any sense or am I going about this wrong? RP was the only synthetic that i saw with similar lower viscosity specs to a dino, but after hearing the negative views on it, i will pass. Either i will stick with a dino oil(hard to find any GL4s) or try another synthetic like Amsoil or Redline and see if I can keep the garage floor clean!!!!
Understandable SR77. If it were me, I'd stick with a dino. I'm not sure what you are looking at accomplishing with a synthetic ... but I'd stick with a dino and change it every 2-3 years instead.
GL4? I think the Coastal gear oils are dual GL4/5 rated ... but I can't confirm that on-line and I don't have a bottle handy.
They are available at Advanced Auto Parts ... in the stores and on-line.
GL4? I think the Coastal gear oils are dual GL4/5 rated ... but I can't confirm that on-line and I don't have a bottle handy.
They are available at Advanced Auto Parts ... in the stores and on-line.
Most GL5 oils are also approved for GL4. Problem is, the additives in GL-5 can have a negative effect on synchronizer performance, that is why many enthusiasts have sought after high quality GL4 only oils.
artificialist, if the bottle says GL4 on it, it is good for GL4. The GL5-damaging-transmissions thing isn't the problem it once was anyway.
SR77, I was out and about today ... running some errands and I ducked into the Albany Advance Auto Parts. The Coastal 75W-90 and 80W-90 gear oils are both approved for GL4. (The 75W-90 I handled was not labeled or priced as a synthetic)
The UPC code numbers are as follows:
75W-90 UPC ends in 159016
80W-90 UPC ends in 124014
The manufacturer is Warren Unilube:
http://www.warrenunilube.com/gearoils.html
They are also labeled as suitable for manual transmissions ... although I'm not sure that means a whole lot.
The UPC code numbers are as follows:
75W-90 UPC ends in 159016
80W-90 UPC ends in 124014
The manufacturer is Warren Unilube:
http://www.warrenunilube.com/gearoils.html
They are also labeled as suitable for manual transmissions ... although I'm not sure that means a whole lot.
Bror Jace,
thanks for your help.
I went in to a Autozone by me too and saw the Coastal 80w-90 and the bottle said GL5, GL4, GL3. Interesting, how can it be both GL5 and GL4? Either it has the high percent of additives in it(GL5) or it doesn't. How can it be both? I see Amsoil rates them both too, not sure if there are other out there that do it too.
Also, Is Coastal known as a decent oil? Do know much about the brand. thanks again
thanks for your help.
I went in to a Autozone by me too and saw the Coastal 80w-90 and the bottle said GL5, GL4, GL3. Interesting, how can it be both GL5 and GL4? Either it has the high percent of additives in it(GL5) or it doesn't. How can it be both? I see Amsoil rates them both too, not sure if there are other out there that do it too.
Also, Is Coastal known as a decent oil? Do know much about the brand. thanks again
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